Constructed wetlands have grown in popularity over the last couple of years mainly because of their natural look and aesthetic appeal. But what exactly is a wetland and just how does it function?
A wetland works just like a biological filter, but instead of creating a waterfall; it creates an area in your pond thick with naturally-filtering plants, as well as rocks and gravel, which provide a surface for bacterial colonization … nature’s perfect filters. So a wetland, while naturally beautiful and pleasing to the eye, is a great filtration method, and will help keep your water looking crystal clear.
One of the greatest things about wetland filtration is that it can be used with almost any system. But will it fit in with your pond? Do you have to have a lot of space to construct a wetland? There are no size limitations because it acts as your biological filtration. The plants, rocks, and gravel act as the filtration media, similar to what you see in nature.
Sure it might look pretty, and it might be designed like a wetland straight out of the marshlands, but how clean does it keep the water? Some say it’s even better than a biological filter, but in actuality, the benefits are very similar. Wetland filtration balances out your water very well, sometimes better than the biological filter, and once it is balanced, your pond will require less water treatment application.
If you install a larger pond with more than one biological filter, the financial benefits of the constructed wetland system will make your customer’s pocketbook pretty happy. If you only have one waterfall, the energy consumption is about the same, but if you have multiple waterfalls, powered by multiple pumps, you can save money by using the wetland system instead.
Learning the Secret
The key to a wetland filtration system lies with the plants. Plants are an integral part of a balanced pond ecosystem and help create a natural looking environment, which is becoming more important to today’s consumer. Plants help purify the water by reducing nutrients, filtering out sediments and absorbing toxic compounds through the process of phytoremediation, they’re also the basis of a food web in which pathogens are consumed by microorganisms associated with the aquatic plants.
Another key to the filtration lies in the sediment chamber created by the AquaBlox® on the bottom of the wetland. This sediment chamber reduces the velocity of the incoming water below 2 feet/second, allowing the sedimentation process to occur while dispersing the water evenly along the bottom of the wetland. The slow, even flow of water is necessary for optimal contact time between the water and gravel bringing nutrients and oxygen to the bacterial colonies. Beneficial bacteria are housed in this gravel, providing your first layer of filtration before the water even hits the plant roots.
The important thing to remember when considering a constructed wetland filter is that, similar to your biological filter’s placement, the wetland filter should be flowing down to your pond for optimal efficiency. The wetland must sit a little higher than the pond because you need the water to flow back into the pond, because the bacteria housed in the wetland will consume dissolved oxygen as they utilize nutrients. This flow of water in the form of a waterfall or swift-moving stream back into the pond is a natural way to re-oxygenate the water.
The Snorkel® and Centipede®
Aquascape snorkel vault and Centipede® Module, along with a layer of small AquaBlox® strategically positioned along the bottom of the filter makes building a wetland simple. All you need to use in conjunction with these two components is a pump appropriate to the amount of water flow, rock and gravel, wetland plants, piping that is appropriate for the size of your pump, a skimmer or wet well, and, of course, water.
The water flows through the plumbing from the wet well or skimmer, into the Centipede Module, which pushes the water into the AquaBlox® sediment chamber up through the layers of gravel where it comes into contact with beneficial bacteria and then the plant roots for final filtration. The Snorkel® Vault is convenient for cleaning any sludge that may accumulate on the bottom through usage. Simply pop off the cap and you have complete access for easy cleaning.
What about the Waterfall?
Maybe your customer wants a wetland but doesn’t want to lose the beauty and sound of a waterfall. No problem! Your customer can have both! You can’t over-filter a pond. It’s virtually impossible. And remember, for large ponds, incorporating both a constructed wetland and waterfall will cost less in operational costs than two waterfalls.
What some installers don’t realize is that your biological filtration actually acts as a wetland filtration system of sorts when you place certain plants in the top of it. Water hyacinth and water lettuce are always a fan favorite, but certain marginals like iris, dwarf cattails, pickerel rush, and any tropicals also work. The important thing to remember is that all of these plants will have to be removed when the cold temperatures hit. You may want to keep some of them in pots for easy removal before the winter winds howl. This may inhibit their filtration a bit, but something’s always better than nothing when it comes to filtration.
So even without a full-fledged constructed wetland system, you can feel comfortable that a wetland of sorts is working in your pond by adding aquatic plants inside the top of the biological filter. After all, the same process is in effect, with water pushing up and through the filter media, and then up through your plant roots.
The bottom line is that constructed wetlands work, and they make any pond look natural and gorgeous. What’s more, natural wetlands and the associated riparian habitats are the most biologically diverse habitats on earth, more species of plants and animals are associated with them than any other type of ecosystem.
But because of our construction practices and changes to natural hydrology, these systems are under great stress. By adding a small wetland in your customer’s backyard, you’ll be helping to preserve the natural biodiversity of your community. With today’s growing tendency toward creating sustainable landscape solutions, you can see why wetland filtration is an obvious choice for today’s environmentally-conscious consumer.
For more information on wetland filtration, watch our short video: